The present disclosure relates generally to wireless communication systems. More particularly, the present disclosure relates to limiting the maximum output power when a mobile wireless device receives a request to transmit in a restricted configuration.
Wireless communication devices have become smaller and more powerful as well as more capable. Increasingly users rely on wireless communication devices for mobile phone use as well as email and Internet access. At the same time, devices have become smaller in size. Devices such as cellular telephones, personal digital assistants (PDAs), laptop computers, and other similar devices provide reliable service with expanded coverage areas. Such devices may be referred to as mobile stations, stations, access terminals, user terminals, subscriber units, user equipment (UE), and similar terms.
A wireless communication system may support communication for multiple wireless communication devices at the same time. In use, a wireless communication device may communicate with one or more base stations by transmissions on an uplink and downlink. Base stations may be referred to as access points, Node Bs, or other similar terms. The uplink or reverse link refers to the communication link from the wireless communication device to the base station, while the downlink or forward link refers to the communication from the base station to the wireless communication devices.
Wireless communication systems may be multiple access systems capable of supporting communication with multiple users (i.e., with mobile user equipment UE) by sharing the available system resources, such as bandwidth and transmit power. Examples of such multiple access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, wideband code division multiple access (WCDMA) systems, global system for mobile (GSM) communication systems, enhanced data rates for GSM evolution (EDGE) systems, and orthogonal frequency division multiple access (OFDMA) systems.
In order to comply with regulatory requirements regarding the emissions into protected radio spectrum, the 3rd Generation Partnership Project (3GPP) has defined scheduling restrictions to prevent operation in scenarios that would cause the UE to violate spectrum emissions requirements. These restrictions are described in the 3GPP TS 36.101 standard, for example.
The possibility exists that the UE may decode a false grant due to poor channel conditions, and this false grant may cause the UE to transmit in a restricted configuration which could potentially lead to excessive emissions in a protected band. A grant for an uplink (UL) transmission is issued by the network after a request from the UE. The UE may request a permission to upload data to a destination via the network. A request for transmission contains data about the state of the transmission buffer and the queue at the UE and its available power margin. A network based scheduler decides when the UE will be granted permission to transmit. Resources are allocated for permission to be granted for UE transmission. If a grant to activate an uplink transmission is falsely detected, UL transmissions could start erroneously and cause interference. If a message activating an UL is received in error, or when none was transmitted, then various problems may occur, including potentially corrupting other uplink transmissions, giving rise to interference in other transmission channels when the UL power level is too high.